/**
 * Copyright (c) 2009 Noel Ang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
package com.lunarshades.samsara.logging;

import java.io.IOException;
import java.io.Writer;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.TimeZone;

/**
 * A Logger whose outlet is a {@link java.io.Writer Writer}. Events are each
 * written to the writer in the following format.
 * <pre>
 * DDD:HH:MM MSG NL
 * </pre>
 * where: DD is the day of the year; HH is the hour of the day (24-hour format);
 * MM is the minute of the hour; MSG is the message specific to the {@link
 * Loggable Loggable} events consumed; and NL is the newline character
 * sequence.
 *
 * @author Noel Ang, sparta.variable@gmail.com
 * @see Logger
 */
public class WriterLogger extends Logger {

public WriterLogger(Writer writer, boolean keepOpen, boolean flushOnlyOnDispose) {
    if (writer == null) {
        throw new NullPointerException();
    }
    mOutlet = writer;
    mDateTimeFormatter = new SimpleDateFormat("DDD:HH:mm");
    mIsDisposed = false;
    mKeepOutletOpen = keepOpen;
    mFlushOnlyOnDispose = flushOnlyOnDispose;
    mMessageBuffer = new StringBuffer(80);
}

/**
 * Consume the specified event.
 *
 * @param event A Loggable object.
 *
 * @throws IllegalStateException if {@link #dispose()} has been previously
 *                               invoked.
 */
public void log(Loggable event) {
    if (!mIsDisposed) {
        if (event == null) {
            return;
        }
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT-0"));
        String time = mDateTimeFormatter.format(calendar.getTime());
        synchronized (mMessageBuffer) {
            mMessageBuffer.append(time)
                    .append(SPACE)
                    .append(event.message())
                    .append(NEWLINE);
            try {
                mOutlet.write(mMessageBuffer.toString());
                if (!mFlushOnlyOnDispose) {
                    mOutlet.flush();
                }
            } catch (IOException e) {
                e.printStackTrace(System.err);
            } finally {
                mMessageBuffer.delete(0, mMessageBuffer.length());
            }
        }
    } else {
        throw new IllegalStateException("Object already disposed.");
    }
}

/**
 * Decides if the specified event is fit for consumption.
 *
 * @param event The event whose suitability is to be determined.
 *
 * @return True if the specified event would cause a subsequent call to the
 *         implementation's {@link #log(Loggable)} to be meaningful; false
 *         otherwise.
 */
public boolean accept(Loggable event) {
    return event != null;
}

/**
 * Discard the logger instance. This method provides a chance for an
 * implementation to free up resources. Once this method is called the object
 * should no longer be used; its behaviour after that point is undefined.
 */
public void dispose() {
    try {
        if (!mKeepOutletOpen) {
            mOutlet.close();
        }
    } catch (IOException e) {
        e.printStackTrace(System.err);
    } finally {
        mIsDisposed = true;
    }
}

private final Writer mOutlet;
private final SimpleDateFormat mDateTimeFormatter;
private final boolean mKeepOutletOpen;
private final boolean mFlushOnlyOnDispose;
private final StringBuffer mMessageBuffer;
private volatile boolean mIsDisposed;
}
